Why do some people faint all of a sudden?

The symptoms are frightening: A rapid heartbeat. Accelerated breathing. A draining of colour form face. Nausea, sweating and ultimately—collapse. During the first hazy moments of awakening, the victim is told that he fainted. What causes this common, if unsettling, experience? In order to function properly, the body’s countless systems must at all times be nourished ...

How is the speed of the wind measured?

By using an apparatus called an anemometer. The commonest type of anemometer is a kind of horizontal three-armed windmill, with a hollow hemispherical cup on the end of each arm (Photo, right). The pressure on the inside of a cup when it is back to wind overcomes the pressure on the rounded front of the ...

How high up are the highest clouds?

Clouds of the kind called cirrus, which is the Latin word for ‘curl,’ float higher than those of any other kind, their average height above sea-level being about 10,000 metres (33,000 feet)—quite more than that of the world’s highest mountain. They are made up of tiny particles of ice, and are always white. They resemble ...

Who invented the Pneumatic tyre?

An engineer, R.W.Thompson, born at Stonehaven, Scotland, in 1822 was the first to invent such tyre. In 1845, Thompson (picture, right) patented a tyre which had an inner tube of canvas made airtight with rubber solution, and an outer cover of leather. A number of these tyres were fitted to road vehicles, but they went ...

Why does laughter bring tears to the eyes?

On the outer side of each eye there is a gland which keeps exuding moisture between the eyeball and the upper eyelid. Ordinarily the fluid is carried away into the nose by a small passage. Hearty laughter, like its opposite emotion, great sorrow, makes the gland give out more liquid than the passage can deal ...